UK Swine flu: yes, we probably over-reacted…

…when it came to the tamiflu advice, anyway.

Less than 5000 cases in January and the National Pandemic Flu Service (NPFS) in England is to be stood down from 11 February.

I wrote the following back in October 2009, and reckon it still stands up. While I think the early response in the UK was justified- indeed pretty impressive- and agree with those who say it’s way too early to make any final judgements, the persistence of the oseltamivir-for-all distribution policy in the UK for so many weeks after the containment phase ended remains baffling. Maybe somebody connected with Roche knows the answer.

The first swine flu cases in the UK were confirmed at the end of April, less than two weeks after the existence of a new strain of H1N1 was verified from recent cases of flu-like illness in the US and Mexico.

Throughout May and the first half of June, the UK response was characterised by the policy of containment. Suspected cases were quarantined, swabbed to confirm the diagnosis, and treated with antivirals such as oseltamivir (initially only after a positive swab). Contacts of cases were swabbed and/or treated to further limit disease spread.

The UK was well prepared for an influenza pandemic. The threat of sustained human-to-human transmission of H5N1 avian influenza (‘bird flu’) was well known. Severe Acute Respiratory Syndrome (SARS), a near-pandemic in 2003, had alerted the world to the speed with which infectious diseases can spread in a globalised society. The Health Protection Agency (HPA) prepared a pandemic contingency plan in 2006, and the government had stockpiled sufficient oseltamivir for half the UK population.

SARS, avian flu, and at least one previous flu pandemic (1918 Spanish flu) were known to have high mortality (>2.5%). Early indications from Mexico suggested that the new H1N1 strain might be significantly more dangerous than seasonal flu. Given this background, a precautionary approach seemed entirely appropriate. Vigorous case-finding and containment in the early stages of the UK outbreak allowed time for the behaviour of the new virus to be characterised, and a head-start to be made on further pandemic planning and development of vaccine. While a policy of containment was in place, and significant uncertainties regarding the virulence of the virus persisted, use of oseltamivir in all suspected cases made sense; even though the clinical benefit of the drug is limited in the vast majority of healthy patients with swine flu (one or two days less symptoms), anything reducing the amount of virus shed from British nasopharynges presumably helped to limit its spread through the population.

Towards the end of June, the accelerating rise in new cases started to overwhelm the resources needed for an effective containment policy, and the UK response entered a ‘mitigation’ phase. It was accepted that swine flu was circulating freely in the population, and that it could no longer be contained. Meanwhile, analyses of cases in the US and Australia appeared to differ from the initial high mortality rates seen in Mexico; it seemed that swine flu might not be so dangerous after all, with rates of serious illness and death similar or only slightly higher than that seen in seasonal flu.

In the UK, an increasing proportion of the population became directly affected by the pandemic in some way, and the media’s response served to magnify public concern (the speed of dissemination of information- and misinformation- facilitated by new media technologies was clearly not a feature of past pandemics). Although suspected cases were no longer being swabbed, the official line remained that antivirals were available to all. News reports picked up on Department of Health projections for the pandemic, inevitably headlining the worst-case scenario. By August, however, the rate of reported influenza-like illness was already starting to fall.

There do seem to be real issues around the mitigation phase of the UK response to the swine flu ‘first wave’, many relating to the use of oseltamivir (tamiflu). Perhaps we should have been quicker to focus attention on the high risk groups, such as those with asthma and the pregnant, and away from the whole population, as soon as it became apparent that the disease was not dangerous in the vast majority of healthy people. Perhaps the limitations of antivirals could have been made clearer (as a relatively new ‘black triangle’ drug, it seems ripe for a scare story of its own, likely focussing on reports of hallucinations when given to children). For several weeks much of the pandemic response effort appeared to be directed at the logistics of distributing sufficient antivirals to the population, rather than emphasizing the importance of simple-but-effective personal hygiene measures.

General practitioners have expressed concerns that important diagnoses were missed or delayed due to protocol-based swine flu diagnoses being made by telephone, rather than face-to-face consultations with a medical professional. The message that a relatively mild viral illness can (and should) be treated with tablets undermines the longstanding, painstaking efforts of public health practitioners and GPs to reduce antibiotic prescribing for respiratory tract infections. The overuse of tamiflu could lead to antiviral resistance in later waves of the pandemic, making it ineffective in the high-risk patients who may gain more benefit from such drugs.

But it has to be remembered that these concerns focus on a period of a few weeks towards the end of what will probably turn out to be the first of several waves of H1N1 pandemic flu, and it’s possible that the virulence and behaviour of the virus may change in later waves. The vigorous initial containment policy seems justified, and whether the more confused responses in the later mitigation phase constitute a serious over-reaction is a judgement likely to be made at a much later stage, with the benefit of several months or years more hindsight.

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